The organic electroluminescence element (hereinafter referred to as “organic EL element”) is a self-luminous type planar light source. Since it produces rapid response, enjoys the advantage of avoiding dependence on the angular field of view, and allows relatively easy addition to dimension and flexibility of the elemental area, it is expected to find a wide range of applications in lighting units and displays.
As the configuration of the organic EL element, the product obtained by forming a transparent electrode (anode) made of indium tin oxide (ITO) on a transparent glass substrate, for example, and superposing thereon a hole injection layer, a hole transfer layer, a light-emitting layer, an electron transfer layer, an electron injection layer, and a cathode by the vacuum deposition method, for example, has been known. In the organic EL element of this configuration, when a DV voltage is applied between the transparent electrode which is an anode and the cathode, the hole (electron hole) injected from the transparent electrode via the hole injection layer is moved via the hole transfer layer to the light-emitting layer while the electron injected from the cathode via the electron injection layer is moved via the electron transfer layer to the light-emitting layer and, in the light-emitting layer, the electron-hole pairs are recombined. As a result, the light of a prescribed wavelength is generated and this light is observed from the transparent glass substrate side.
Incidentally, when the organic EL element mentioned above is intended to effect temporal modulation of brightness within a prescribed image plane with a view to attaining an effect of visual sense, for example, it is generally required to adopt a configuration proper for a display device similarly to various kinds of display. In a display having light-emitting elements arrayed in the pattern of a matrix, for example, when the picture elements in each vertical line are equalized in brightness, the individual lines are so adjusted that they sequentially grow in brightness from right to left in the image plane, and the display is scrolled from left to right at a certain frequency, the image plane appears to be waving. The display of this behavior cannot be realized unless it is furnished with a display panel having picture elements (light-emitting elements) innumerably arrayed and a control device composed of a driver IC and a CPU that are capable of enabling the individual picture elements to emit light with accurate brightness at a proper timing.
As displays using an organic EL element, various methods of display as disclosed in JP-A 2003-76324 and JP-A 2002-91377, for example, have been known. These methods, however, invariably necessitate their picture elements severally possessing a configuration proper for an organic EL element to be arrayed in the pattern of a matrix and indispensably require a scanning line and a signal wire serving in conformity with these signal elements, a switching element, and driving circuits for driving and controlling them.